Depilatory



Patented Apr. 39), 11940 STATES PATENT OFFICE DEPILATORY William B.Stoddard and Junuo'noi-un. New York, N. r.

6 Claims.

This application is a division of our co-pending apglication Serial No.47,973 filed November 2, 19 5.

Our invention relates to a depilatory composition having a stabilized,soluble s'tannite as the active ingredient.

Heretofore depilatories have been formed with a sulphide as the. activeingredient. The sulphide, while effective as a depilatory agent, has avery oflensive odor which renders its use ofiensive and disagreeable. Ithas been'known that the alkali stannites,.-which are free fromobjectionable odors of the sulphide and have substantially no odor, alsohave the property of destroy ing hair substance. The alkali stannitesare, however, very active substances and tend to decompose, forming inone reaction stannates with the simultaneous production of metallic tinand, in another reaction with water, forming stannous oxide and thehydroxide of the alkali metal.

These decompositions have heretofore been an obstacle to the use ofstannites as depilatory agents because, in the commercial use ofdepilatories, it is necessary that they be capable of being storedwithout substantial deterioration or decomposition for long periods oftime as,.for example, for several months or a, year, in which time theymay be distributed, transported and sold in the retail trade.

Attempts have been made heretofore to stabilize the soluble stannites inthe presence of a strongly alkaline solution. Not only, however, has thestability of such solutions as heretofore made been uncertain, but thepresence .of the alkali or alkaline reacting substances in the solutionis irritating to the skin, particularly as several minutes are requiredfor the action of the stannite on the hair, and contact of a stronglyalkaline solution with the skin for such a period of time is highlyirritating.

These various disadvantages are. obviated by our present invention whichprovides a stable stannite depilatory capable of being stored for longperiods of time and having only a limited or i a very slight alkalinityinsuflicient to irritate the skin under normal conditions of use.

In our present invention we form a soluble stannite,' such as sodiumstannite, potassium stannite or other alkali stannite, in an aqueoussolution that is not strongly. alkaline as, for example, one that has apH value less than 12.6 and which also contains a stabilizer active in asolution of this low alkalinity. The stabilizers suitable for thispurpose are of a class consisting of water soluble organic compoundshaving three or more carbinol hydroxy groups, or three bydroxy groupsother than those in a carboxyl group. Examples of such organic compoundshaving three or more hydroxy groups are triethanolamine, glycerine,dextrine, gum tragacanth, and the sugars such as cane sugar, glucose,

or other hexoses or pentoses.

After the stabilized solution of the stannite has been formed, it may bediluted somewhat if its concentration is too great and then mixed withother compounding ingredients such as finely ground kaolin or clay, orother earthy materials inert to the substances contained in thesolution, to form a paste. The material thus formed may be packed intubes or jars and will remain stable over long periods of timesuflicient to enable it to be transported and stored until sold.

It will be understood that the sodium or other soluble stannites may beformed in any suitable manner by chemical or electro-chemical reactions.

The following is an example of the method of formation of a stannitesuitable for the purpose of our invention.

The stannite maybe economically produced by adding to an appropriateamount of caustic alkali solution, in which the proper quantity ofstabilizer has been dissolved, the equivalent amount of stannous saltsolution. The concentration of both the alkali and stan'nous saltsolution should be such as toyield a stannite solution ofrequisitestrength. The normality of the stannous solution should, therefore, bedetermined in advance so that the required amount of sodium hydroxidemay be used to form the stannite without having an excess. For example,454 grams of chemically pure stannous chloride (SnClaZEO) were added to450 c. c. of water. Analysis of the resulting solution showed that itwas. 6.225 normal in'tin, and 6.65 normal with respect to the free andcombined hydrochloric acid, or a total of 12.8'75 normal for thecombined reaction. Therefore, 1 c.c. of the stannous solution willrequire 12.875 c. c. of normal sodium hydroxide or alkali hydroxide tocombine with the chloride radicle and with the resulting stannoushydroxide.

For this purpose a. 10% solution of sodium hydroxide was carefullystandardized and found to be exactly 2.5 normal. It is, therefore,evident that 25 c. c. of the tin solution requires 128.8 0. c. of the10% sodium hydroxide solution. These solutions were used in each of thefollowing examples.

Example! 10 c. c. of triethanolamine were added to 128.8 c. c. of the10% sodium hydroxide solution and the solution was then heated to 65 C.25 c; c. of the tin solution were then added and the solution heated to80 C., with constant stirring. A

clear solution of sodium stannite resulted and all of the reagentsremained in solution except for a trace or small amount of impuritieswhich were present in the reagents. The solution was made up to a volumeof 175 c. c. and filtered to remove the traces of impurities and toleave a colorless sparkling filtrate. The pH value of this solution was12.22. It was capable of removing very coarse hair in five minuteswithout irritating the skin, its alkalinity being relatively much lessthan that oi. solutions in which stability is sought by excess alkalisuch solutions generally having a pH value or 12.6 or twice thealkalinity of the above solution. The resulting stannite solution wasthen mixed with a suitable filler, such as kaolin and, upon filling intotubes or Jars, remained stable and unafiected for long periods of timesuch, for example, as tenmonths or longer, without decomposition ordeterioration. Other fillers, such as precipitated chalk or earthymaterials, may be employed, but those are preferred which are inert as.for example, kaolin.

Example II In this example the same procedure was followed as in ExampleI except that 10 grams of cane sugar were substituted for thetriethanolamine. In this case a quantity 01' white insoluble matterremained at 80 C. but substantially all of it dissolved when boiled overa tree flame. The resulting stannite solution is non-irritating andstable.

Example III The procedure of Example I was followed except that 10 c. c.of glycerine were substituted for the triethanolamine. The same resultwas obtained, the reagents dissolving to a clear solution at 80 C.,except for traces of. impurities present in the original solution.

All or the above pH values were determined electrometrically.

The solutions made up in Examples II and III may be mixed with an inertfiller, such as kaolin, and filled into jars as described in Example I.

It will be understood that the above are merely given by way of examplesof materials from the class of stabilizers which consists of organiccompounds having at least three hydroxyl groups. It will be understood,for example, that others of the wide group of tri-hydroxy orpoly-hydroxy organic compounds may be used, those being selected,however, which are'themselves stable unpreparations.

der the conditions or reaction and of storage for a period of time.

The stabilizers as used in the examples aczomplish three things- I 1st.They prevent the decomposition oi the stannous hydroxide which is firstformed on adding the stannous salt to the alkali solution containingthem. a

2nd. They permit the solution of the stannous hydroxide in thetheoretical amount of alkali hydroxide.

3rd. They stabilize the alkali stannite solution after it is formed.

In our invention it is also possible to obtain sodium stannite solutionsoi. a concentration much greater than that required for depilatory By asuitable selection of the concentration of the reagents as, for example,using a 40% solution of sodium hydroxide, a correspondingly strongersolution or the tin and a proportionately more concentrated stannitesolution is obtained.

The electrometric determinations! pH values as to sodium ionconcentration is by direct uncorrected reading using a glass electrodeinasmuch as a hydrogen electrode cannot be used accurately because 01.the reducing action of the material. For the same reason colorimetricmeasurements using indicators are not satisfactory.

What we claim is- 1. A soluble stannite solution having a pH value ofless than 12.6 and containing organic compounds having more thanthreealcoholic hydroxyl groups as stabilizers.

2. A soluble stannite solution having a pH value of about 12.3 or lessand containing a stabilizer of the class consisting of organic compoundshaving at least three alcoholic hydroxyl r up I 3. A soluble stannitesolution containing sodium stannite and triethanolamine and having a pHvalue 0! less than 12.6.

4. A method of stabilizing soluble stannite solutions which comprisesadding thereto a stabilizer of the class consisting! organic compoundshaving at least three alcoholic hydroxyl groups.

5. A method of forming a stable soluble stannite solution whichcomprises adding a stannous salt to an alkali hydroxide containing astabilizer of the group consistingof organic compounds having at leastthree alcoholic hydroxyl groups. 6. A soluble stannite solution having apH value of less than 12.6 and containing a stabilizer comprisingorganic compounds containing at least 1 three alcoholic hydroxyl groups.

W. B. SI'ODDARD. JULIUS 3m.

